There is an increasing use of touchscreen displays in a variety of fields. A common problem to solve is how to confirm a touch, and there is substantial prior art on ways to obtain this. One example is US20110181523A1 which discloses how the signals of the touch position coordinates of a first and a second sensor array are compared, and if they do not coincide, the touch is invalidated. In some fields, such as for example avionics, process control, bank terminals etc, there are additional safety-critical requirements to consider.